|Humenik, Frank - NC STATE UNIV|
|Rice, J - NC STATE UNIV|
|Scalf, Gary - MURPHY FAMILY FARMS|
Submitted to: International Symposium on Agricultural & Food Processing Wastes Proceeding
Publication Type: Proceedings
Publication Acceptance Date: May 10, 1995
Publication Date: N/A
Interpretive Summary: Modern swine production produces enormous amounts of wastewater. An acceptable method of wastewater treatment is the use of constructed wetlands. Constructed wetlands are an effective method for mass removal of nitrogen from swine wastewater but less effective for phosphorus removal. However, it is difficult to obtain effluents with nutrient levels that meet tregulatory discharge concentrations when nutrient loads are high. An alternative to solve this problem is to include an oxidative pretreatment that will reduce total organic carbon, increase nitrification/ denitrification rates and remove considerable amounts of phosphorus before the wastewater enters the constructed wetland for treatment. Land treatment systems other than terminal land application are being investigated to enhance the constructed wetland performance to treat wastewater. An overland flow and a media filter pretreatment are currently ybeing evaluated to determine if more effective nitrogen and phosphorus mas removal can be obtained.
Technical Abstract: Constructed wetlands are an acceptable method for mass removal of nutrients from animal wastewaters. However, dischargeable effluent concentrations are difficult to achieve. The study objectives were to determine if a dischargeable effluent could be obtained from a constructed wetland treatment system with a loading of 3 kg TKN/ha/day and to determine mass removals for nitrogen and phosphorus. Wetland system mass removal of TKN was >90%, and effluent total nitrogen concentrations could have met local stream discharge requirements during some time periods. Wetland system mass removal of TP was only about 73%, and effluent TP concentrations generally exceeded discharge allowances. As nutrients build up and the wetland systems become a carbon generator, it will be difficult to meet stream discharge requirements with constructed wetlands for swine wastewater treatment. However, effluent TOC levels are inconsequential for terminal land application. Therefore, an enhanced wetland treatment system at the increased loading rate of 10 kg TKN/ha/day including an overland flow and an alternative media filter pretreatment is being evaluated to determine if more effective nitrogen and phosphorus mass removal can be obtained.